Antiglobulin reagents were developed (see Z01 DE 00236 04 CPR) or obtained commercially. Horseradish peroxidase (HRP), oralkaline phosphatase (AP) conjugated antispecies reagents were from commercial sources. Orthophenylenediamine (ODP), 2,2'-Azino-di-(3-ethylbenzthiozoline sulfonic acid) (ABTS) were tested as substrates for HPD, and paranitrophenylphosphate was used as substrate for AP. Assays were performed in polystyrene or polyvinyl, flat bottom 96 well microtiter plates. Whole bacterial cells attached well to polystyrene while polyvinyl was better for carbohydrate antigens. The concentration of cells or antigens bound to the well varied between 0.1 - 100 g. Tween 20 and/or bovine serum albumin (BSA)) were incorporated in the diluents to eliminate non-specific binding. HRP conjugates were more sensitive than AP conjugates, and OPD gave more intense color development than ABTS. Rat antiglobulin reagents raised in the rabbit had natural antibacterial antibodies which gave rise to high background. It was necessary to absorb these reagents prior to their use in ELISA.